The prevalence of Pseudomonas species in freshwater fish and water from aquaculture farms in Turkey was determined on a monthly basis, in the period covering 2013–2017 and two seasons of 2018. The ...farms included in the study were located in six different regions of Turkey. A total of 90 Pseudomonas strains were isolated from water and diseased and healthy fish, and were classified under 20 species. The phenotypic characterization of the strains was based on oxidase and catalase activities, haemolysis, tolerance to temperature and sodium chloride, the production of fluorescent pigments and antibiotic resistance spectra. The phylogenetic identification of the 90 isolates was performed by a 4-gene multilocus sequence analysis, based on the partial sequencing of the 16S rRNA, gyrB, rpoB and rpoD genes. This is the first report on the isolation of several Pseudomonas species, namely, P. brenneri, P. defensor, P. haemolytica, P. lactis, P. lundensis, P. lurida, P. mandelii, P. meridiana, P. migulae, P. proteolytica, P. simiae, and P. weihenstephanensis, from freshwater salmonid fish. Two of these species, P. haemolytica and P. lactis have been isolated for the first time from fish farms, an environment quite different from their original isolation source, raw milk. Furthermore, seven putative new Pseudomonas species were isolated from water and farmed rainbow trout. During the 2013 to 2018 period, several Pseudomonas species were detected to have spread from the Aegean and Central Anatolia regions to the Eastern Anatolia and Black Sea regions.
•Ninety Pseudomonas strains isolated from water fish, were classified under 20 species.•First report on the isolation of 12 Pseudomonas species from freshwater salmonid fish•Seven putative new Pseudomonas species isolated from water and farmed rainbow trouts
Cu(NN
)
ClO
is a copper (I) complex, where NN
is an imine ligand 6-((quinolin-2-ylmethylene) amino)-2H-chromen-2-one obtained by derivatization of natural compound coumarin, developed for the ...treatment of infectious diseases that affect salmonids. In previous research, we showed that the Cu(I) coordination complex possesses antibacterial activity against
, providing protection against this pathogen in rainbow trout during challenge assays (with an RPS of 50%). In the present study, the effects of administering Cu(NN
)
ClO
to
over a 60-days period were evaluated with regard to systemic immune response and its potential to alter intestinal microbiota composition. In
, an immunostimulatory effect was evident at days 30 and 45 after administration, resulting in an increment of transcript levels of IFN-γ, IL-12, TNF-α, lysozyme and perforin. To determine whether these immunomodulatory effects correlated with changes in the intestinal microbiota, we analyzed the metagenome diversity by V4 16S rRNA sequencing. In
, both Cu(NN
)
ClO
and commercial antibiotic florfenicol had comparable effects at the phylum level, resulting in a predominance of proteobacteria and firmicutes. Nonetheless, at the genus level, florfenicol and Cu(NN
)
ClO
complex exhibited distinct effects on the intestinal microbiota of
. In conclusion, our findings demonstrate that Cu(NN
)
ClO
is capable of stimulating the immune system at a systemic level, while inducing alterations in the composition of the intestinal microbiota in
.
A study of 91 isolates from fish farms in Turkey showed that isolates P7T, P11, P24b, P29, P72, P73 and P158 belonged to the genus Pseudomonas according to 16S rRNA nucleotide sequence analysis. The ...analysis of the sequences of the RNA polymerase sigma factor gene (rpoD) located these strains in the Pseudomonas fluorescens lineage of species within the P. fluorescens subgroup, close to the cluster composed of the species Pseudomonas grimontii, Pseudomonas marginalis and Pseudomonas panacis. Based on similarities in the 16S rRNA and rpoD gene sequences of three previously isolated strains from other origins (CCUG 57209, CCUG 62357 and W5.2-93) linked them to the same cluster. A polyphasic taxonomic approach including phenotypic characterization, fatty acid composition, and multilocus sequence analysis, together with whole-cell MALDI-TOF data, corroborated this assumption. The genome G+C mol% contents were 59.48 and 59.71, respectively. The average nucleotide indices based on BLAST analysis and the genome-to-genome distance calculation for the P7T and CCUG 57209 strains with their closest relative, P. grimontii, were 88.16–88.29% and 38.10–38.20%, respectively. These data confirm that isolates P7T, P11, P24b, P29, P72, P73, P158, CCUG 57209, CCUG 62357 and W5.2-93 represent a new species for which the name Pseudomonas sivasensis is proposed, with P7T as a type strain (=CCUG 74260T= and CECT30107T).
Metranidazole (MTZ) is an antibiotic used for parasitic infections in a number of species. Accumulation of this drug in the environment and its interaction with fish of economic value makes this drug ...particularly important. In the present study, we examined the histopathological effects of MTZ on the intestinal tissue of Oncorhynchus mykiss.
The fish in aquarium were exposed to MTZ at doses of 5, 10, 20 mg/L for 2, 4 and 8 days. At the end of the experiments, macroscopic pathology or death were not observed at these doses. Histochemical staining with Haematoxylene-Eosin, Periodic Acid Schiff and Gomori Trichrome showed, depending on increased dose and prolonged duration, areas of necrosis, edema, inflammation, small tears at the tips of the villi and excretion with heterogenic distribution of the Goblet cells. Moreover, changes in the connective tissue of the intestines due to toxicity of MTZ and decreases in immunostaining of matrix proteins such as laminin and collagen IV, especially in the epithelium were observed.
Findings of the present study would be useful to demonstrate the adverse effects of MTZ use, emphasizing the importance of the effect on fish which could be very important public health.
•The toxic effect of metronidazole on fish tissues.•The alterations of matrix proteins due to toxic effect of metronidazole.•The effect of widespread use of antibiotic on environmental pollution.•The pollution effect of metronidazole on aquatic organisms which also danger for environmental and public health.
•Juvenile rainbow were exposed to Pine and Eucalyptus PPME along with an in situ bioassay downstream of the combined discharge.•Fish exposed to PPME showed induced levels of plasma vitellogenin and ...female gonad maturation.•Male fish showed intersex characteristics in laboratory and in situ assays.•Tertiary treated PPME from Eucalyptus production have stronger estrogenic effects on juvenile fish.
Pulp and paper mill effluents (PPMEs) have been shown to increase gonad size, cause early maturation, and disrupt hormone functions in native and non-native Chilean fish. In this study, we assessed reproductive (plasma vitellogenin; VTG, gonad development) and metabolic (ethoxyresorufin-O-deethylase activity; EROD) end points, relative liver size (LSI) and condition factor (K) of juvenile female and male rainbow trout exposed to effluents. Unlike previous studies, which have focus either on the specific effects of effluent on fish in laboratory exposures or biotic population statuses downstream of discharge sites, we simultaneously assessed the impacts of PPMES on trout using two approaches: (1) laboratory exposures of tertiary treated PPME produced from processing Eucalyptus globulus or Pinus radiata; and (2) in situ bioassay downstream of the combined discharge of the same pulp mill. Despite an increase in the average gonadosomatic index (GSI) in exposed fish, no statistical differences in gonad size between exposed and unexposed individuals was detected. However, both female and male fish exposed to effluents showed significantly higher concentrations of plasma VTG, so more in fish exposed to Eucalyptus-based effluent when compared to Pinus PPME. In addition, male fish showed intersex characteristics in all exposure assays (Eucaliptus and Pinus) and, despite the low concentration of effluent in the river (<1% v/v), similar responses were observed in the caged fish. Finally, EROD activity was induced in both in situ exposures and laboratory assays at the higher PPME concentration (60–85% PPME). This study confirms estrogenic effects in Chilean fish exposed to PPME and the necessity for biological effects monitoring in addition to the assessment of physical–chemical endpoints as required in current government regulations.
The effects of indigenous probiotics Lactobacillus plantarum and Lactobacillus pentosus alone, and in combination with β-1,3-glucan in juvenile rainbow trout (Oncorhynchus mykiss) were investigated. ...Eight groups were defined: control (G1), 1% β-1,3-glucan (G2), L. plantarum (G3), L. pentosus (G4), L. plantarum + L. pentosus (G5), L. plantarum with 1% β-1,3-glucan (G6), L. pentosus with 1% β-1,3-glucan (G7) and L. plantarum + L. pentosus with 1% β-1,3-glucan (G8). After eight weeks, the innate immune responses were elevated in all treated groups; however, synergistic effects were observed for anti-trypsin, bactericidal activity and respiratory burst activity in groups 7 and 8. Although the other immune responses were higher in treated groups, they did not make statistically significant differences. Checking microbiota showed that β-1,3-glucan improved conditions of indigenous probiotics. The diet 8 caused significant alterations in the intestinal microbiota by significantly decreasing the proportion of total count bacteria to lactic acid bacteria, which were demonstrated by reducing the total number of bacteria in Group 8 compared to the control group.
ABSTRACT An experimental infection with Aeromonas salmonicida, in rainbow trout (Oncorhynchus mykiss) was performed. In order to compare the daily alterations of the hematological parameters and ...glucose-6-phosphate dehydrogenase activity, blood samples were taken 1,3,7,14 and 21 days after the infection. Total red blood cell values, were significantly decreased in 7 and 21th day, a significant decrease in hemoglobin concentration noted only in the 21th day, significantly lower values in hematocrit, were observed at 7, 14 and 21th days, total leucocyte and thrombocyte counts, found significantly higher only in the 3th day, comparing with the control group. While, significantly increasing tendency were determined in mean corpuscular volume and mean corpuscular hemoglobin values from 7th day to the end of the experiment, no significant alterations in mean corpuscular hemoglobin concentration values noted. Fish belong to the infected group, revealed significant increase in G6PDH enzyme activity in the first and seventh days of infection.
Defining reliable and objective biomarkers of sperm quality is a complex matter, because it does not rely on a particular characteristic of the milt. Susceptibility to cryopreservation varies between ...ejaculations and throughout the year, and the evaluation of fresh sperm does not always provide accurate information about their fertilization ability after freezing and thawing. DNA is one of the cell components prone to suffering cryodamage and several studies have pointed out the importance of the maintenance of its integrity during sperm cryostorage. The authors analysed sperm from rainbow trout for four weeks during the natural reproductive season. Viability, DNA integrity, and fertilization ability were evaluated. Furthermore, in order to increase membrane and DNA protection during sperm cryopreservation, the authors optimized the use of LDL fraction from egg yolk as a cryoprotectant during the analysed period. Results revealed that the evaluation of DNA damage in fresh sperm reveals subtle cell damage, not evidenced in fresh sperm by the other parameters. DNA fragmentation increased from 8 to 31% during the reproductive season, indicating pre-freezing differences that render the cells more susceptible to cryodamage. Also, the use of 12% LDL (low density lipoprotein) fraction, instead of the commonly used pure egg yolk, improved sperm quality after freezing. When LDL was used, post-thaw quality remained constant throughout the analysed period, providing around 60% of eyed embryos. In contrast, when egg yolk was used, post-thaw quality decreased significantly at the end of the season and the percentage of eyed embryos dropped from 60% to 27%. Results demonstrated that reduction in DNA integrity takes place during the reproductive season affecting susceptibility to cryodamage and that the protective effect of egg yolk is very much improved when only their LDL fraction is added to the cryopreservation extender.
Diets containing deoxynivalenol (DON) were fed to rainbow trout Oncorhynchus mykiss (Walbaum) for 4 weeks followed by experimental infection (intraperitoneal) with Flavobacterium psychrophilum ...(4.1 × 10⁶ colony‐forming units CFU mL⁻¹). Mortality of rainbow trout fed either 6.4 mg kg⁻¹ DON or trout pair‐fed the control diet was significantly reduced (P < 0.05) in comparison with trout fed the control diet to apparent satiation (<0.1 mg kg⁻¹ DON). In a second experiment, trout were fed one of three experimental diets; a control diet, a diet produced with corn naturally contaminated with DON (3.3 mg kg⁻¹ DON) or a diet containing purified DON (3.8 mg kg⁻¹); however, these fish were not experimentally infected. The presence of DON resulted in significant reduction (P < 0.0001) in feed intake as well as weight gain after 4 weeks. Respiratory burst of head‐kidney leucocytes isolated from rainbow trout fed diets containing purified DON (3.8 mg kg⁻¹) was significantly higher (P < 0.05) at 35 day post‐exposure compared with controls. The antimicrobial activity of DON was examined by subjecting F. psychrophilum in vitro to serial dilutions of the chemical. Complete inhibition occurred at a concentration of 75 mg L⁻¹ DON, but no effect was observed below this concentration (0–30 mg L⁻¹).
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